1. Field of the Invention
The present invention relates to portable, manually operable pump sprayer units for the spraying of liquids or fluids. More particularly, the present invention relates to a manual pump assembly which is received within a conventional liquid container.
2. Description of the Related Art
Portable pump sprayers are typically used for dispensing fluids such as herbicides, cleaning fluids, insecticides, fertilizers, paints, and various other liquids. Conventional portable pump sprayers include a reservoir dimensioned to hold a predetermined volume of liquid, a manual pump assembly which threadingly and sealingly engages a fill opening of the reservoir, a discharge valve, and a spray wand with a nozzle from which the fluid is discharged. The fill opening typically has a minimum diameter of greater than approximately five or six inches and may be as large as approximately twelve inches or greater. The fill opening is typically threaded and receives the manual pump assembly. The manual pump assembly is also threaded and engages the threads of the fill opening. The reservoir of a conventional pump sprayer, in addition to holding the liquid to be sprayed, serves the function of a pressure chamber.
In operation of a conventional pump sprayer, the reservoir/pressure chamber initially contains air at atmospheric pressure and the fluid to be sprayed. The operation of the pump forces air into the reservoir/pressure chamber, thereby increasing the pressure of the air therein to a point substantially greater than atmospheric pressure. The compressed air, in turn, exerts pressure on the fluid contained in the reservoir/pressure chamber. Operation of the discharge valve allows the elevated pressure within the reservoir/pressure chamber to push the fluid out through the nozzle until the valve is closed or equilibrium is reached. The compressed air which exerts pressure on the liquid, however, also exerts that same substantial pressure upon the walls of the reservoir/pressure chamber itself. Thus, the reservoir/pressure chamber must be constructed in a manner and from materials which will withstand and contain the pressure. Therefore, typical reservoirs/pressure chambers are constructed of strong materials, such as stainless steel or aluminum, which are relatively expensive, require special handling and manufacturing techniques, and which are relatively heavy.
Many of the liquids which are ultimately applied by spraying from a portable pump sprayer are distributed and sold to consumers at the retail level in lightweight, thin-walled containers made from plastic. Such containers typically hold a half-gallon or more of liquid. Due to their lightweight construction, the retail containers are not capable of withstanding the substantially elevated internal pressure that is necessary to facilitate the spray application of a liquid from a reservoir. Thus, the retail containers can not perform the function of a pressure chamber. Even if the retail containers were capable of withstanding the internal pressure required for spray application, most manual pump assemblies from conventional pump sprayers are too large to be attached to the small diameter openings found on typical retail containers. Thus, if it is desired to apply by spraying a liquid that is supplied in a typical retail container, a consumer is forced to purchase a separate sprayer unit. The liquid must be poured from the retail container into the sprayer unit and then applied.
An example of a pump unit which includes a pressure chamber that is separate from the reservoir is provided by, for example, U.S. Pat. No. 5,816,454, issued to the present inventor. That pump unit includes a two-part enlarged pressure chamber and a pump. In use, the enlarged pressure chamber is fluidly connected to a reservoir holding fluid to be sprayed. The reservoir may be a conventional container. The enlarged pressure chamber is attached to the reservoir fill opening. The pressure chamber has a diameter that is substantially larger than the reservoir fill opening. Thus, substantially the entire pressure chamber is disposed externally of the reservoir, above the fill opening. The assembly thus formed has several disadvantages.
The disposition of the pressure chamber external to and above the reservoir results in an assembly of substantially larger size and height than the reservoir itself. Thus, the assembly is somewhat cumbersome to carry and manipulate. An impact upon the pressure chamber of the assembly places a great amount of stress on the interface between the pressure chamber and the reservoir to which it is attached. The height of the pressure chamber creates a lever or moment arm which magnifies the stress placed on that interface as a result of any force exerted upon the pressure chamber. The disposition of the pressure chamber external to and above the reservoir, under certain circumstances, creates further disadvantages.
The reservoir may be a conventional liquid container. Such conventional liquid containers are typically of a lightweight construction and will weigh substantially less than a pressure chamber which must be constructed of a more substantial, and therefore heavier, material. When the weight of the volume of liquid in the container is approximately equal to or less than the combined weight of the pressure chamber and any liquid contained therein, the application of a slight force to the pressure chamber will upset and/or topple the assembly. Thus, as the volume of fluid in the container decreases, the degree of instability will progressively increase. Furthermore, the fill opening of a many conventional liquid containers is not disposed on the exact vertical center of gravity of the container. Thus, where a sufficient difference in weight exists between the pressure chamber and a container with an off-center fill opening, the assembly will be inherently unstable. If the assembly is not inherently unstable, any shifting of fluid within the container or within the pressure chamber can result in rendering the assembly unstable and the toppling of the assembly.
The configuration of the assembly also makes operation of the pump cumbersome. When the location of the fill opening does not coincide with the vertical center of gravity of the container, the force exerted on the pump will create a force on the container. This force will have a horizontal component and will act on the container. The horizontal component of that force will be amplified by the pressure chamber acting as a moment arm. Thus, in order to prevent the downward force required to operate the pump from toppling the assembly a user will likely have to stabilize the assembly while pumping.
Moreover, the configuration of the assembly results in a rather unwieldy item from a marketing and distribution standpoint. Packaging, shipping, and displaying the pump unit in an assembled and ready to use configuration is rendered inefficient due to the disposition of the pressure chamber external to and above the container. Specially designed, extra tall shipping containers and a greater spacing between retail display shelves would be required, thereby wasting valuable transportation and display space.
Therefore, what is needed in the art is a manual pump assembly having a pressure chamber which can be disposed substantially entirely within a typical retail liquid container or reservoir.
Furthermore, what is needed in the art is a manual pump assembly for use with a typical retail liquid container or reservoir which is substantially stable when in its use position and during operation.
Moreover, what is needed in the art is a manual pump assembly which is conveniently, efficiently, and easily packaged with a liquid container for distribution and display at the retail level.